The present invention relates to an inhalation device, in particular, an inhalation device for administering a powdered medicament by inhalation from a blister pack.
It is known in the treatment of respiratory conditions to make use of dry powder inhalers comprising a suction tube arranged so that it is able to cooperate with a blister pack containing a plurality of individual blisters each holding a dose of powdered medicament.
Reference should now be made to WO 97/40876 which discloses an inhalation device comprising a suction tube and a blister pack assembly. The blister pack assembly is in the form of a carrier which holds the blister pack. The carrier is configured such that the upper surface has a plurality of holes which sit above the blisters in the blister pack thereby enabling the distal end of the suction tube to penetrate the blisters as and when required.
The object of the present invention is to provide an improved inhalation device of this kind which has a superior construction and is more user-friendly. In particular, the construction should be light and compact whilst retaining sufficient rigidity and strength bearing in mind that the user may have to administer the powdered medicament at frequent intervals. Moreover, the construction should be such that the user cannot misuse the inhalation device since incorrect delivery of the powdered medicament could be potentially harmful to the user.
According to the present invention, there is provided a blister pack having a plurality of blisters each holding a dose of a powdered medicament comprising a lower base containing a plurality of cavities for the powdered medicament and an upper sealing foil layer which covers the lower base to form the blisters, wherein each cavity is provided with at least one adjacent slit formed by scoring the foil layer and lower base, the slit ensuring accurate penetration of a cavity by a suction tube through which a user can inhale the contents of the cavity.
Preferably, the opposed edges of a slit are folded back towards the lower base to facilitate penetration by the suction tube.
Preferably, a scored slit sits at a distance of approximately 2 mm from the cavity perimeter.
In a further aspect, the present invention also provides a blister pack assembly comprising the blister pack and a carrier for the blister pack.
Preferably, the carrier comprises an upper tray and a lower tray which are interconnectable around the blister pack, the upper tray being provided with a plurality of holes and slots which sit above and correspond with the positions of the cavities and slits in the blister pack.
Preferably, the lower tray is provided with a plurality of slots which sit below and correspond with the slits in the blister pack.
In yet a further aspect, the present invention provides an inhalation device comprising the blister pack assembly and a suction tube which is constructed for cooperation with the blister pack assembly having a distal end which can penetrate the foil above a cavity, a proximal end through which the user inhales and at least one guide arm which accurately locates the distal end of the suction tube in a cavity by penetrating the blister pack assembly.
Preferably, the guide arm or arms have a tapered configuration to facilitate location in the blister pack assembly.
Preferably, the suction tube is removably hinged to the carrier by way of cooperating elements on the guide arm or arms and the carrier.
Preferably, the guide arm or arms are provided with a shallow channel which facilitates relocation of the suction tube on the hinge.
Preferably, the distal end of the suction tube is constructed to ensure there is an air gap between the suction tube and the blister pack assembly when the suction tube penetrates a blister.